Hydraulic shovel calibration system and hydraulic shovel calibration method

ABSTRACT

A current position computation unit of a hydraulic shovel computes a current position of a working point included in a work tool based on a plurality of parameters that indicate the dimensions and swing angles of a boom, an arm, and the work tool. A vehicle body coordinate system computation unit of a calibration device computes coordinate conversion information based on first and second working point position information measured by an external measurement device. A coordinate conversion unit converts coordinates at a plurality of positions of the working point measured by the external measurement device in a coordinate system of the external measurement device to those in a vehicle body coordinate system using the coordinate conversion information. A calibration computation unit computes calibration values of the parameters based on the converted coordinates at the plurality of positions of the working point in the vehicle body coordinate system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2011-065977 filed on Mar. 24, 2011, the disclosure of which is herebyincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a hydraulic shovel calibration systemand a hydraulic shovel calibration method.

BACKGROUND ART

From the past, there is known a hydraulic shovel provided with aposition detection device which detects the current position of aworking point of a work implement. For example, in the hydraulic shoveldisclosed in Japanese Laid-open Patent Application Publication No.2002-181538, position coordinates of a cutting edge of a bucket arecomputed based on position information from a GPS antenna. Specifically,position coordinates of the cutting edge of the bucket are computedbased on parameters such as a positional relationship of the GPS antennaand a boom pin, lengths of each of a boom, an arm, and the bucket, andeach of the direction angles of the boom, the arm, and the bucket.

SUMMARY

Accuracy of the position coordinates of the cutting edge of the bucketwhich have been computed is affected by the accuracy of the parametersdescribed above. However, these parameters normally have errors withregard to design values. As a result, the parameters are measured usinga measurement means such as a measuring tape during initial settings ofthe position detection device of the hydraulic shovel. However, it isnot easy to accurately measure the parameters as described above using ameasurement means such as a measuring tape. In addition, in a case wherethere are a high number of parameters, a considerable amount of time isnecessary in order to measure all of these parameters and this isburdensome.

In addition, the accuracy of position detection using the positiondetection device is confirmed after the parameters that have beenmeasured are input into the position detection device. For example, theposition coordinates of the cutting edge of the bucket are directlymeasured using GPS. Then, the position coordinates of the cutting edgeof the bucket which have been computed using the position detectiondevice are compared to the position coordinates of the cutting edge ofthe bucket which are directly measured by a GPS measurement device. In acase where the positional coordinates of the cutting edge of the bucketwhich have been computed using the position detection device and thepositional coordinates of the cutting edge of the bucket which aredirectly measured by the GPS measurement device do not match,determining of the parameters using a measuring tape and inputting theparameters to the position detection device are repeated until theposition coordinates match. That is, the values of the parameters arerearranged until the actual value and the computed value of the positioncoordinates match. An extremely long amount of time is necessary forsuch calibration work and this is burdensome.

An object of the present invention is to provide a calibration systemand a calibration method for a hydraulic shovel which can improve theaccuracy of position detection of a working point and shortencalibration work time.

A hydraulic shovel calibration system according to a first aspect of thepresent invention is provided with a hydraulic shovel, a calibrationdevice, and an external measurement device. The hydraulic shovelincludes a travel unit, a pivoting body, a work implement, an angledetection unit, and a current position computation unit. The pivotingbody is rotatably attached to the travel unit. A boom is swingablyattached to the pivoting body. An arm is swingably attached to the boom.A work tool is swingably attached to the arm. The angle detection unitdetects a swing angle of the boom with respect to the pivoting body, aswing angle of the arm with respect to the boom, and a swing angle ofthe work tool with respect to the arm. The current position computationunit computes the current position of a working point included in thework tool based on a plurality of parameters that indicate thedimensions and the swing angles of the boom, the arm, and the work tool.The calibration device is a device for calibrating the parameters. Theexternal measurement device is a device that measures the position ofthe working point. In addition, the calibration device includes an inputunit, a vehicle body coordinate system computation unit, a coordinateconversion unit, and a calibration computation unit. The input unit is aunit where first working point position information and second workingpoint position information are input. The first working point positioninformation either includes at least two positions of the working pointwhere the posture of the work implement is different and a position of apredetermined reference point on an action plane of the work implement,at least the two positions and the position of the predeterminedreference point being measured by the external measurement device, orincludes at least three positions of the working point where the postureof the work implement is different, at least the three positions beingmeasured by the external measurement device. The second working pointposition information includes at least three positions of the workingpoint where the rotation angle of the pivoting body with respect to thetravel unit is different. The vehicle body coordinate system computationunit computes a first unit normal vector perpendicular to the actionplane of the work implement based on the first working point positioninformation. The vehicle body coordinate system computation unitcomputes a second unit normal vector perpendicular to a rotation planeof the pivoting body based on the second working point positioninformation. The vehicle body coordinate system computation unitcomputes a third unit normal vector perpendicular to the first unitnormal vector and the second unit normal vector. The coordinateconversion unit converts coordinates at a plurality of positions of theworking point measured by the external measurement device in thecoordinate system of the external measurement device to those in thevehicle body coordinate system of the hydraulic shovel using the firstunit normal vector, the second unit normal vector, and the third unitnormal vector. The calibration computation unit computes calibrationvalues of the parameters based on the converted coordinates at theplurality of positions of the working point in the vehicle bodycoordinate system.

A hydraulic shovel calibration system according to a second aspect ofthe present invention is the hydraulic shovel calibration systemaccording to the first aspect wherein the vehicle body coordinate systemcomputation unit computes an intersection vector of the action plane ofthe work implement and a rotation plane of the pivoting body. Thevehicle body coordinate system computation unit computes, as the secondunit normal vector, a unit normal vector of a plane which passes throughthe intersection vector of the action plane of the work implement andthe rotation plane and which is perpendicular to the action plane of thework implement.

A hydraulic shovel calibration system according to a third aspect of thepresent invention is the hydraulic shovel calibration system accordingto the first aspect wherein the first working point position informationincludes coordinates of a plurality of positions which are differentpositions in the upward and downward direction of the work implementand/or which are different positions in the front and back direction ofthe vehicle body.

A hydraulic shovel calibration system according to a fourth aspect ofthe present invention is the hydraulic shovel calibration systemaccording to the first aspect wherein the parameters include a firstdistance, a second distance, and a third distance. The first distance isa distance between a swing pivot of the boom with respect to thepivoting body and a swing pivot of the arm with respect to the boom. Thesecond distance is a distance between the swing pivot of the arm withrespect to the boom and a swing pivot of the work tool with respect tothe arm. The third distance is a distance between the swing pivot of thework tool with respect to the arm and the working point. The currentposition computation unit computes the current position of the workingpoint in the vehicle body coordinate system based on the first distance,the second distance, the third distance, and the swing angles. Thecalibration computation unit computes the calibration values of thefirst distance, the second distance, and the third distance based oncoordinates at a plurality of positions of the working point which aremeasured by the external measurement device and converted into thevehicle body coordinate system.

A hydraulic shovel calibration system according to a fifth aspect of thepresent invention is the hydraulic shovel calibration system accordingto any one of the first to fourth aspects wherein the externalmeasurement device is a total station.

A hydraulic shovel calibration method according to a sixth aspect of thepresent invention is a method for calibrating parameters in a hydraulicshovel. The hydraulic shovel includes a travel unit, a pivoting body, awork implement, an angle detection unit, and a current positioncomputation unit. The pivoting body is rotatably attached to the travelunit. A boom is swingably attached to the pivoting body. An arm isswingably attached to the boom. A work tool is swingably attached to thearm. The angle detection unit detects a swing angle of the boom withrespect to the pivoting body, a swing angle of the arm with respect tothe boom, and a swing angle of the work tool with respect to the arm.The current position computation unit computes the current position of aworking point included in the work tool based on a plurality ofparameters that indicate the dimensions and the swing angles of theboom, the arm, and the work tool. The hydraulic shovel calibrationmethod comprises the following first step to fifth step. The first stepis measuring the position of a working point using an externalmeasurement device. The second step is inputting first working pointposition information and second working point position information intoa calibration device for calibrating the parameters. The firstinformation either includes at least two positions of the working pointwhere the posture of the work implement is different and a position of apredetermined reference point on an action plane of the work implement,at least the two positions and the position of the predeterminedreference point being measured by the external measurement device orincludes at least three positions of the working point where the postureof the work implement is different, at least the three positions beingmeasured by the external measurement device. The second working pointposition information includes at least three positions of the workingpoint where the rotation angle of the pivoting body with respect to thetravel unit is different. The third step is computing a first unitnormal vector perpendicular to the action plane of the work implementbased on the first working point position information, a second unitnormal vector perpendicular to the rotation plane of the pivoting bodybased on the second working point position information, and a third unitnormal vector perpendicular to the first unit normal vector and thesecond unit normal vector, using the calibration device. The fourth stepis converting coordinates at a plurality of positions of the workingpoint measured by the external measurement device in the coordinatesystem of the external measurement device to those in the vehicle bodycoordinate system of the hydraulic shovel using the first unit normalvector, the second unit normal vector, and the third unit normal vector,using the calibration device. The fifth step is computing calibrationvalues of the parameters based on the converted coordinates at theplurality of positions of the working point in the vehicle bodycoordinate system, using the calibration device.

In the hydraulic shovel calibration system according to the first aspectof the present invention, the coordinates at the plurality of positionsof the working point which are measured using the external measurementdevice are converted into the vehicle body coordinate system. Then, thecalibration values of the parameters are computed based on the convertedcoordinates at the plurality of positions of the working point in thevehicle body coordinate system. As a result, it is not necessary toactually measure the values of the parameters using a measurement meanssuch a measuring tape. Alternatively, it is possible to reduce thenumber of parameters for which actual measurement is necessary. Inaddition, it is not necessary to perform rearrangement of the values ofthe parameters until the actual value and the computed value in theposition coordinates match. Hereby, in the hydraulic shovel calibrationsystem according to the present invention, it is possible to improve theaccuracy of position detection of the working point and to shorten thecalibration work time as well.

In the hydraulic shovel calibration system according to the secondaspect of the present invention, a unit normal vector perpendicular to arotation plane specified from second working point position informationis not used as the second unit normal vector. But at first, theintersection vector of the action plane of the work implement and therotation plane of the pivoting body is computed. Then, a unit normalvector of a plane, which passes through the intersection vector of theaction plane of the work implement and the rotation plane and which isperpendicular to the work implement, is computed as the second unitnormal vector. As a result, even in a case where the action plane of thework implement and the rotation plane of the pivoting body are notstrictly perpendicular, it is possible to accurately compute the vehiclebody coordinate system. Hereby, it is possible to further improve theaccuracy of position detection of the working point.

In the hydraulic shovel calibration system according to the third aspectof the present invention, the coordinates of the position of the swingpivot of the boom with respect to the pivoting body and the position ofthe working point with various work implement postures are included infirst working point position information. As a result, it is possible toaccurately compute the first unit normal vector perpendicular to theaction plane of the work implement.

In the hydraulic shovel calibration system according to the fourthaspect of the present invention, the first distance, the seconddistance, and the third distance are included in the parameters. Thecurrent position computation unit computes the current position of theworking point based on these distances. In addition, conversely bymeasuring the current position of the working point using the externalmeasurement device, it is possible to accurately compute the calibrationvalues of the first distance, the second distance, and the thirddistance from measurement results of the external measurement device.

In the hydraulic shovel calibration system according to the fifth aspectof the present invention, it is possible to easily measure the firstoperation position information and the second operation positioninformation using the total station.

In the hydraulic shovel calibration system according to the sixth aspectof the present invention, the coordinates of the plurality of positionsof the working point which are measured by the external measurementdevice are converted into the vehicle body coordinate system. Then, thecalibration values of the parameters are computed based on the convertedcoordinates of the plurality of positions of the working point in thevehicle body coordinate system. As a result, it is not necessary toactually measure the values of the parameters using a measurement meanssuch as a measuring tape. Alternatively, it is possible to reduce thenumber of parameters for which actual measurement is necessary. Inaddition, it is not necessary to perform rearrangement of the values ofthe parameters until the actual value and the computed value in theposition coordinates match. Hereby, in the hydraulic shovel calibrationmethod according to the present invention, it is possible to improve theaccuracy of position detection of the working point and to shorten thecalibration work time as well.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective diagram of a hydraulic shovel according to anembodiment of the present invention.

FIGS. 2( a) to 2(c) are diagrams schematically illustrating aconfiguration of the hydraulic shovel.

FIG. 3 is a block diagram illustrating a configuration of a controlsystem provided with the hydraulic shovel.

FIG. 4 is a diagram illustrating an example of a configuration of designterrain.

FIG. 5 is a diagram illustrating an example of a guidance screen.

FIG. 6A is a table indicating a list of parameters.

FIG. 6B is a table indicating a list of parameters.

FIG. 7 is a side view of a boom.

FIG. 8 is a side view of an arm.

FIG. 9 is a side view of a bucket and the arm.

FIG. 10 is a side view of the bucket.

FIG. 11 is a diagram illustrating a method for computing parameters thatindicate the length of cylinders.

FIG. 12 is a flow chart illustrating a work sequence performed by anoperator during calibration.

FIG. 13 is a diagram illustrating a setting position of an externalmeasurement device.

FIG. 14 is a side view of a position of a cutting edge in five posturesof a work implement.

FIG. 15 is a table listing stroke lengths of cylinders corresponding toeach position of a first to a fifth position.

FIG. 16 is a top view illustrating positions of a first measurementpoint and a second measurement point on a reference antenna.

FIG. 17 is a top view illustrating positions of a third measurementpoint and a fourth measurement point on a direction antenna.

FIG. 18 is a top view illustrating three positions of a cutting edgewhere rotation angles are different.

FIG. 19 is a diagram illustrating an example of an operation screen of acalibration device.

FIG. 20 is a functional block diagram illustrating a processing functionrelated to calibration by the calibration device.

FIG. 21 is a diagram for explaining a computing method of coordinateconversion information.

FIG. 22 is a diagram for explaining a computing method of coordinateconversion information.

DESCRIPTION OF THE EMBODIMENTS 1. Configuration 1-1. OverallConfiguration of Hydraulic Shovel

Below, a calibration system and calibration method for a hydraulicshovel according to a first embodiment of the present invention will bedescribed with reference to the drawings. FIG. 1 is a perspectivediagram of a hydraulic shovel 100 which executes calibration using thecalibration system. The hydraulic shovel 100 has a vehicle body 1 and awork implement 2. The vehicle body 1 has a pivoting body 3, a cab 4, anda travel unit 5. The pivoting body 3 is pivotally attached to the travelunit 5. The pivoting body 3 includes devices such as a hydraulic pump 37(refer to FIG. 3), an engine which is not shown, and the like. The cab 4is placed on a front portion of the pivoting body 3. A display inputdevice 38 and an operation device 25 which will be described later aredisposed in the cab 4 (refer to FIG. 3). The travel unit 5 has crawlertracks 5 a and 5 b and the hydraulic shovel 100 moves due to rotation ofthe crawler tracks 5 a and 5 b.

The work implement 2 is attached to a front portion of the vehicle body1, and has a boom 6, an arm 7, a bucket 8, a boom cylinder 10, an armcylinder 11, and a bucket cylinder 12. A base end portion of the boom 6is swingably attached to a front portion of the vehicle body 1 with aboom pin 13. That is, the boom pin 13 corresponds to a swing pivot ofthe boom 6 with respect to the pivoting body 3. The base end portion ofthe arm 7 is swingably attached to a tip end portion of the boom 6 withan arm pin 14. That is, the arm pin 14 corresponds to a swing pivot ofthe arm 7 with respect to the boom 6. The bucket 8 is swingably attachedto a tip end portion of the arm 7 with a bucket pin 15. That is, thebucket 15 corresponds to a swing pivot of the bucket 8 with respect tothe arm 7.

FIGS. 2( a) to 2(c) are diagrams schematically illustrating aconfiguration of the hydraulic shovel 100. FIG. 2( a) is a side view ofthe hydraulic shovel 100. FIG. 2( b) is a rear view of the hydraulicshovel 100. FIG. 2( c) is a top view of the hydraulic shovel 100. Asshown in FIG. 2( a), L1 is a length of the boom 6, i.e., a lengthbetween the boom pin 13 and the arm pin 14, which is equivalent to afirst distance of the present invention. L2 is a length of the arm 7,i.e., a length between the arm pin 14 and the bucket pin 15, which isequivalent to a second distance of the present invention. L3 is a lengthof the bucket 8, i.e., a length between the bucket pin 15 and a cuttingedge P of the bucket 8, which is equivalent to a third distance of thepresent invention.

The boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12which are shown in FIG. 1 are hydraulic cylinders each of which aredriven using hydraulic pressure. A base end portion of the boom cylinder10 is swingably attached to the pivoting body 3 with a boom cylinderfoot pin 10 a. In addition, a tip end portion of the boom cylinder 10 isswingably attached to the boom 6 with a boom cylinder top pin 10 b. Theboom cylinder 10 expands and contracts by using hydraulic pressure todrive the boom 6. A base end portion of the arm cylinder 11 is swingablyattached to the boom 6 with an arm cylinder foot pin 11 a. In addition,a tip end portion of the arm cylinder 11 is swingably attached to thearm 7 with an arm cylinder top pin 11 b. The arm cylinder 11 expands andcontracts by using hydraulic pressure to drive the arm 7. A base endportion of the bucket cylinder 12 is swingably attached to the arm 7with a bucket cylinder foot pin 12 a. In addition, a tip end portion ofthe bucket cylinder 12 is swingably attached to one end of a first linkmember 47 and one end of a second link member 48 with a bucket cylindertop pin 12 b. The other end of the first link member 47 is swingablyattached to the tip end portion of the arm 7 with a first link pin 47 a.The other end of the second link member 48 is swingably attached to thebucket 8 with a second link pin 48 a. The bucket cylinder 12 expands andcontracts by using hydraulic pressure to drive the bucket.

FIG. 3 is a block diagram illustrating a configuration of a controlsystem which the hydraulic shovel 100 comprises. First to third angledetection units 16 to 18 are respectively provided in the boom 6, thearm 7, and the bucket 8. The first to third angle detection units 16 to18 are stroke sensors and indirectly detect a swing angle of the boom 6with respect to the vehicle body 1, a swing angle of the arm 7 withrespect to the boom 6, and a swing angle of the bucket 8 with respect tothe arm 7 by respectively detecting the stroke lengths of the cylinders10 to 12. Specifically, the first angle detection unit 16 detects thestroke length of the boom cylinder 10. A display controller 39 whichwill be describer later computes a swing angle α of the boom 6 withrespect to the z axis of a vehicle body coordinate system shown in FIG.2( a) from the stroke length of the boom cylinder 10 which is detectedby the first angle detection unit 16. The second angle detection unit 17detects the stroke length of the arm cylinder 11. The display controller39 computes a swing angle β of the arm 7 with respect to the boom 6 fromthe stroke length of the arm cylinder 11 which is detected by the secondangle detection unit 17. The third angle detection unit 18 detects thestroke length of the bucket cylinder 12. The display controller 39computes a swing angle γ of the bucket 8 with respect to the arm 7 fromthe stroke length of the bucket cylinder 12 which is detected by thethird angle detection unit 18. A method for computing the swing anglesα, β, and γ will be described in detail later.

As shown in FIG. 2( a), a position detection unit 19 is provided in thevehicle body 1. The position detection unit 19 detects the currentposition of the vehicle body 1 of the hydraulic shovel 100. The positiondetection unit 19 has two antennas 21 and 22 for RTK-GNSS (Real TimeKinematic—Global Navigation Satellite Systems) which are shown in FIG. 1and a three-dimensional position sensor 23 which is shown in FIG. 2( a).The antennas 21 and 22 are arranged to be separated by a certaindistance along the y axis (refer to FIG. 2( c)) of the vehicle bodycoordinate system x-y-z which will be described later. A signalaccording to GNSS radio waves received by the antennas 21 and 22 isinput into the three-dimensional position sensor 23. Thethree-dimensional position sensor 23 detects the current position of theantennas 21 and 22 in a global coordinate system. Here, the globalcoordinate system is a coordinate system which is measured using GNSSand is a coordinate system with respect to an origin which is fixed onthe earth. In contrast to this, the vehicle body coordinate system whichwill be described later is a coordinate system with respect to an originwhich is fixed on the vehicle body 1 (specifically, the pivoting body3). The antenna 21 (referred to below as the “reference antenna 21”) isan antenna for detecting the current position of the vehicle body 1. Theantenna 22 (referred to below as the “direction antenna 22”) is anantenna for detecting the orientation of the vehicle body 1(specifically, the pivoting body 3). The position detection unit 19detects the angle of direction of the x axis of the vehicle bodycoordinate system in the global coordinate system which will bedescribed later using the positions of the reference antenna 21 and thedirection antenna 22. Here, the antennas 21 and 22 may be GPS antennas.

As shown in FIG. 3, a roll angle sensor 24 and a pitch angle sensor 29are provided in the vehicle body 1. The roll angle sensor 24 detects aninclination angle θ1 (referred to below as the “roll angle θ1”) in thewidthwise direction of the vehicle body 1 with respect to the directionof gravity (the vertical direction) as shown in FIG. 2( b). Here, in theembodiment, the widthwise direction has the meaning of the widthwisedirection of the bucket 8 and matches with the vehicle widthwisedirection. However, the widthwise direction of the bucket 8 and thevehicle widthwise direction may not match in a case where the workimplement 2 is provided with a tilt bucket which will be describedlater. The pitch angle sensor 29 detects an inclination angle θ2(referred to below as the “pitch angle θ2”) in the front and backdirection of the vehicle body 1 with respect to the direction of gravityas shown in FIG. 2( a).

As shown in FIG. 3, the hydraulic shovel 100 comprises the operationdevice 25, a work implement controller 26, a work implement controldevice 27, and the hydraulic pump 37. The operation device 25 has a workimplement operation member 31, a work implement operation detection unit32, a travel operation member 33, a travel operation detection unit 34,a rotation operation member 51, and a rotation operation detection unit52. The work implement operation member 31 is a member for an operatorto operate the work implement 2 and is, for example, an operation lever.The work implement operation detection unit 32 detects details ofoperation inputted by using the work implement operation member 31 andtransmits the details to the work implement controller 26 as a detectionsignal. The travel operation member 33 is a member for an operator tooperate the travelling of the hydraulic shovel 100 and is, for example,an operation lever. The travel operation detection unit 34 detectsdetails of operation inputted by using the travel operation member 33and transmits the details to the work implement controller 26 as adetection signal. The rotation operation member 51 is a member for anoperator to operate the rotation of the pivoting body 3 and is, forexample, an operation lever. The rotation operation detection unit 52detects details of operation inputted by using the rotation operationmember 51 and transmits the details to the work implement controller 26as a detection signal.

The work implement controller 26 has a storage unit 35 such as a RAM ora ROM and a computation unit 36 such as a CPU. The work implementcontroller 26 mainly controls the actions of the work implement 2 andthe rotation of the pivoting body 3. The work implement controller 26generates a control signal for causing the work implement 2 to carry outactions according to the operation of the work implement operationmember 31 and outputs the control signal to the work implement controldevice 27. The work implement control device 27 has a hydraulic controlmachine such as a proportional control valve. The work implement controldevice 27 controls the flow amount of hydraulic fluid which is suppliedfrom the hydraulic pump 37 to the hydraulic cylinders 10 to 12 based onthe control signal from the work implement controller 26. The hydrauliccylinders 10 to 12 are driven according to the hydraulic fluid which issupplied from the hydraulic pump 37. Hereby, the work implement 2carries out the actions. In addition, the work implement controller 26generates a control signal in order to carry out rotation of thepivoting body 3 according to the operation of the rotation operationmember 51 and outputs the control signal to a rotation motor 49. Hereby,the rotation motor 49 is driven and rotation of the pivoting body 3 iscarried out.

1-2. Configuration of Display System 28

A display system 28 is mounted in the hydraulic shovel 100. The displaysystem 28 is a system for providing information to an operator in orderto form a shape such as a design surface which will be described laterby digging the ground surface in a work area. The display system 28 hasthe display input device 38 and the display controller 39.

The display input device 38 has an input unit 41 like a touch panel anda display unit 42 such as an LCD. The display input device 38 displays aguidance screen for providing information for digging operation. Inaddition, various types of keys are displayed in the guidance screen.The operator can execute various types of functions of the displaysystem 28 by touching the various types of keys on the guidance screen.The guidance screen will be displayed later in detail.

The display controller 39 executes the various types of functions of thedisplay system 28. The display controller 39 and the work implementcontroller 26 are able to communicate with each other using a wirelessor wired communication means. The display controller 39 has a storageunit 43 such as a RAM or a ROM and a computation unit 44 such as a CPU.The computation unit 44 executes various types of computations in orderto display the guidance screen based on various types of data stored inthe storage unit 43 and the detection results of the position detectionunit 19.

Design terrain data is created in advance and stored in the storage unit43 of the display controller 39. The design terrain data is informationrelating to the three-dimensional shape and positions of the designterrain. The design terrain indicates a target shape of the groundsurface which is a work target. The display controller 39 displays theguidance screen on the display input device 38 based on the designterrain data and data from the detection result of the various types ofsensors described above. Specifically, the design terrain is configuredusing a plurality of design surfaces 45 which are each represented by atriangular polygon as shown in FIG. 4. Here, only some out of theplurality of design surfaces in FIG. 4 are given the reference numeral45 and the reference numerals of the other design surfaces are omitted.The operator selects one or a plurality of the design surfaces 45 out ofthe design surfaces 45 as a target surface 70. The display controller 39displays the guidance screen on the display input device 38 in order tonotify the operator of the position of the target surface 70.

2. Guidance Screen

Below, the guidance screen will be described in detail. The guidancescreen is a screen which indicates the positional relationship of thetarget surface 70 and the cutting edge of the bucket 8 and for guidingthe work implement 2 of the hydraulic shovel 100 so that the groundsurface which is the target surface becomes a shape which is the same asthe target surface 70.

2-1. Configuration of Guidance Screen

A guidance screen 53 is illustrated in FIG. 5. The guidance screen 53includes an upper view 53 a illustrating the design terrain of the workarea and the current position of the hydraulic shovel 100 and a sideview 53 b illustrating the positional relationship of the target surface70 and the hydraulic shovel 100.

The upper view 53 a on the guidance screen 53 represents the designterrain as viewed from above using a plurality of triangular polygons.More specifically, the upper view 53 a represents the design terrainwith the rotation plane of the hydraulic shovel 100 as a projectionsurface. Accordingly, the upper view 53 a is a view directly from abovethe hydraulic shovel 100 and the design surfaces 45 tilt when thehydraulic shovel 100 tilts. In addition, the target surface 70 selectedfrom the plurality of design surfaces 45 is displayed with a differentcolor from the other design surfaces 45. Here, the current position ofthe hydraulic shovel 100 is shown in FIG. 5 with a hydraulic shovel icon61 as seen from above but may be displayed using another symbol. Inaddition, the upper view 53 a includes information for bringing thehydraulic shovel 100 directly face-to-face with the target surface 70.The information for bringing the hydraulic shovel 100 directlyface-to-face with the target surface 70 is displayed as a facing compass73. The facing compass 73 is an icon indicating a direction directlyfacing the target surface 70 and a direction of the hydraulic shovel 100to rotate. The operator can confirm the degrees to which the shovelfaces the target surface 70 using the facing compass 73.

The side view 53 b of the guidance screen 53 includes an image showingthe positional relationship of the target surface 70 and the cuttingedge of the bucket 8 and the distance information 88 indicating thedistance between the target surface 70 and the cutting edge of thebucket 8. Specifically, the side view 53 b includes a design surfaceline 81, a target surface line 82, and an icon 75 of the hydraulicshovel 100 as seen from the side. The design surface line 81 indicates across section of the design surfaces 45 other than the target surface70. The target surface line 82 indicates a cross section of the targetsurface 70. As shown in FIG. 4, the design surface line 81 and thetarget surface line 82 are obtained by computing an intersection 80 ofthe design surface 45 and a plane 77, which passes through the currentposition of a midpoint P of the cutting edge of the bucket 8 in thewidthwise direction (referred to below simply as the “cutting edge ofthe bucket 8”). The method for computing the current position of thecutting edge of the bucket 8 will be described in detail later.

As above, the relative positional relationship of the design surfaceline 81, the target surface line 82, and the hydraulic shovel 100including the bucket 8 is displayed in the guidance screen 53 usingimages. The operator can set the cutting edge of the bucket 8 to movealong the target surface line 79 so that the current terrain becomes thedesign terrain, which leads to easy operation of digging.

2-2. Cutting Edge Position Computation Method

Next, the method for computing the position of the cutting edge of thebucket 8 described above will be described in detail. The computationunit 44 of the display controller 39 computes the current position ofthe cutting edge of the bucket 8 based on the detection results of theposition detection unit 19 and a plurality of parameters stored in thestorage unit 43. Lists of parameters stored in the storage unit 43 areshown in FIGS. 6A and 6B. The parameters include work implementparameters and antenna parameters. The work implement parameters includea plurality of parameters that indicate the dimensions and the swingangles of the boom 6, the arm 7, and the bucket 8. The antennaparameters include a plurality of parameters that indicate thepositional relationship of the antennas 21 and 22 and the boom 6. Asshown in FIG. 3, the computation unit 44 of the display controller 39has a first current position computation unit 44 a and a second currentposition computation unit 44 b. The first current position computationunit 44 a computes the current position of the cutting edge of thebucket 8 in the vehicle body coordinate system based on the workimplement parameters. The second current position computation unit 44 bcomputes the current position of the cutting edge of the bucket 8 in theglobal coordinate system from the antenna parameters, the currentpositions of the antennas 21 and 22 in the global coordinate systemwhich are detected by the position detection unit 19, and the currentposition of the cutting edge of the bucket 8 in the vehicle bodycoordinate system which is computed by the first current positioncomputation unit 44 a. Specifically, the current position of the cuttingedge of the bucket 8 is obtained as follows.

First, as shown in FIG. 2, the vehicle body coordinate system x-y-z isset whose origin is the intersection of the shaft of the boom pin 13 andthe action plane of the work implement 2 which will be described later.Here, the position of the boom pin 13 in the description below means aposition of a midpoint of the boom pin 13 in the vehicle widthwisedirection. In addition, the current swing angles α, β, and γ of the boom6, the arm 7, and the bucket 8 respectively, which are described above,are computed from the detection results of the first to the third angledetection units 16 to 18. The method for computing the swing angles α,β, and γ will be described later. The coordinates (x, y, z) of thecutting edge of the bucket 8 in the vehicle body coordinate system arecomputed with equation 1 below using the swing angles α, β, and γ of theboom 6, the arm 7, and the bucket 8 respectively and the lengths L1, L2,and L3 of the boom 6, the arm 7, and the bucket 8 respectively.x=L1 sin α+L2 sin(α+β)+L3 sin(α+γ)y=0z=L1 cos α+L2 cos(α+β)+L3 cos(α+β+γ)  Equation 1

In addition, the coordinates (x, y, z) of the cutting edge of the bucket8 in the vehicle body coordinate system which are obtained from equation1 are converted to coordinates (X, Y, Z) in the global coordinate systemusing equation 2 below.

$\begin{matrix}{\begin{pmatrix}X \\Y \\Z\end{pmatrix} = {{\begin{pmatrix}{\cos\;\kappa\;\cos\;\varphi} & {{\cos\;\kappa\;\sin\;\varphi\;\sin\;\omega} + {\sin\;\kappa\;\cos\;\omega}} & {{{- \cos}\;\kappa\;\sin\;\varphi\;\cos\;\omega} + {\sin\;\kappa\;\sin\;\omega}} \\{{- \sin}\;\kappa\;\cos\;\varphi} & {{{- \sin}\;\kappa\;\sin\;\varphi\;\sin\;\omega} + {\cos\;\kappa\;\cos\;\omega}} & {{\sin\;\kappa\;\sin\;\varphi\;\cos\;\omega} + {\cos\;\kappa\;\sin\;\omega}} \\{\sin\;\varphi} & {{- \cos}\;\varphi\;\sin\;\omega} & {\cos\;\varphi\;\cos\;\omega}\end{pmatrix}\begin{pmatrix}x \\y \\z\end{pmatrix}} + \begin{pmatrix}A \\B \\C\end{pmatrix}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

Here, ω, φ, and κ are expressed as below.

$\omega = {\arcsin\left( \frac{\sin\mspace{11mu}\theta\; 1}{\cos\;\varphi} \right)}$φ = θ 2 κ = −θ 3

Here, as described above, θ1 is the roll angle. θ2 is the pitch angle.In addition, θ3 is a yaw angle and is a direction angle of the x axis ofthe vehicle body coordinate system in the global coordinate system whichis described above. Accordingly, the yaw angle θ3 is computed based onthe positions of the reference antenna 21 and the direction antenna 22which are detected by the positioned detection unit 19. (A, B, C) arecoordinates of the origin of the vehicle body coordinate system in theglobal coordinate system. The antenna parameters described aboveindicate the positional relationship of the antenna 21 and 22 and theorigin of the vehicle body coordinate system, i.e., the positionalrelationship of the antennas 21 and 22 and the midpoint of the boom pin13 in the vehicle widthwise direction. Specifically, as shown in FIG. 2(b) and FIG. 2( c), the antenna parameters include a distance Lbbxbetween the boom pin 13 and the reference antenna 21 in the x axialdirection of the vehicle body coordinate system, a distance Lbby betweenthe boom pin 13 and the reference antenna 21 in the y axial direction ofthe vehicle body coordinate system, and a distance Lbbz between the boompin 13 and the reference antenna 21 in the z axial direction of thevehicle body coordinate system. In addition, the antenna parametersinclude a distance Lbdx between the boom pin 13 and the directionantenna 22 in the x axial direction of the vehicle body coordinatesystem, a distance Lbdy between the boom pin 13 and the directionantenna 22 in the y axial direction of the vehicle body coordinatesystem, and a distance Lbdz between the boom pin 13 and the directionantenna 22 in the z axial direction of the vehicle body coordinatesystem. (A, B, C) is computed based on the antenna parameters and thecoordinates of the antennas 21 and 22 in the global coordinate system,where the antennas 21 and 22 are detected.

As shown in FIG. 4, the display controller 39 computes the intersection80 of the three-dimensional design terrain and the plane 77 which passesthrough the cutting edge of the bucket 8, based on the current positionof the cutting edge P of the bucket 8 computed as described above andthe design terrain data stored in the storage unit 43. Then, the displaycontroller 39 computes a portion out of the intersection 80 which passesthrough the target surface 70 as the target surface line 82 describedabove. A portion out of the intersection 80 other than the targetsurface line 82 is computed as the design surface line 81.

2-3. Method for Computing Swing Angles α, β, and γ

Next, a method for computing the current swing angles α, β, and γ of theboom 6, the arm 7, and the bucket 8 from the detection results of thefirst to the third angle detection units 16 to 18 will be described.

FIG. 7 is a side view of the boom 6. The swing angle α of the boom 6 isexpressed by equation 3 below with the work implement parameters shownin FIG. 7.

$\begin{matrix}{\alpha = {{\arctan\left( {- \frac{Lboom2\_ x}{Lboom2\_ z}} \right)} - {\arccos\left( \frac{{{Lboom}\; 1^{2}} + {{Lboom}\; 2^{2}} - {boom\_ cyl}^{2}}{2 \star {{Lboom}\; 1*{Lboom}\; 2}} \right)} + {\arctan\left( \frac{Lboom1\_ z}{Lboom1\_ x} \right)}}} & {{Equation}\mspace{14mu} 3}\end{matrix}$

As shown in FIG. 7, Lboom_(—)2x is a distance between the boom cylinderfoot pin 10 a and the boom pin 13 in the horizontal direction of thevehicle body 1 where the boom 6 is attached (that is, equivalent to thex axial direction in the vehicle body coordinate system). Lboom_(—)2z isa distance between the boom cylinder foot pin 10 a and the boom pin 13in the vertical direction of the vehicle body 1 where the boom 6 isattached (that is, equivalent to the z axial direction in the vehiclebody coordinate system). Lboom1 is a distance between the boom cylindertop pin 10 b and the boom pin 13. Lboom2 is a distance between the boomcylinder foot pin 10 a and the boom pin 13. boom_cyl is a distancebetween the boom cylinder foot pin 10 a and the boom cylinder top pin 10b. Lboom1_z is a distance between the boom cylinder top pin 10 b and theboom pin 13 in a zboom axial direction. Here, a direction which linksthe boom pin 13 and the arm pin 14 as seen from the side is set as anxboom axis and a direction that is perpendicular to the xboom axis isset as a zboom axis. Lboom1_x is a distance between the boom cylindertop pin 10 b and the boom pin 13 in an xboom axial direction.

FIG. 8 is a side view of the arm 7. The swing angle β of the arm 7 isexpressed by equation 4 below using the work implement parameters whichare shown in FIG. 7 and FIG. 8.

$\begin{matrix}{\beta = {{\arctan\left( {- \frac{Lboom3\_ z}{Lboom3\_ x}} \right)} + {\arccos\left( \frac{{{Lboom}\; 3^{2}} + {{Larm}\; 2^{2}} - {arm\_ cyl}^{2}}{2 \star {{Larm}\; 3*{Larm}\; 2}} \right)} + {\arctan\left( \frac{Larm2\_ x}{Larm2\_ z} \right)} + {\arctan\left( \frac{Larm1\_ x}{Larm1\_ z} \right)} - \pi}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

As shown in FIG. 7, Lboom3_z is a distance between the arm cylinder footpin 11 a and the arm pin 14 in the zboom axial direction. Lboom3_x is adistance between the arm cylinder foot pin 11 a and the arm pin 14 inthe xboom axial direction. Lboom3 is a distance between the arm cylinderfoot pin 11 a and the arm pin 14. As shown in FIG. 8, Larm2 is adistance between the arm cylinder top pin 11 b and the arm pin 14. Asshown in FIG. 7, arm_cyl is a distance between the arm cylinder foot pin11 a and the arm cylinder top pin 11 b. As shown in FIG. 8, Larm2_x is adistance between the arm cylinder top pin 11 b and the arm pin 14 in anxarm2 axial direction. Larm2_z is a distance between the arm cylindertop pin 11 b and the arm pin 14 in a zarm2 axial direction. Here, adirection which links the arm cylinder top pin 11 b and the bucket pin15 as seen from the side is set as an xarm2 axis and a direction that isperpendicular to the xarm2 axis is set as a zarm2 axis. Larm1_x is adistance between the arm pin 14 and the bucket pin 15 in the xarm2 axialdirection. Larm1_z is a distance between the arm pin 14 and the bucketpin 15 in the zarm2 axial direction. Here, a direction which links thearm pin 14 and the bucket pin 15 as seen from the side is set as anxarm1 axis. The swing angle 13 of the arm 7 is an angle which is formedby the xboom axis and the xarm1 axis.

FIG. 9 is a side view of the bucket 8 and the arm 7. FIG. 10 is a sideview of the bucket 8. The swing angle γ of the bucket 8 is expressed byequation 5 below using the work implement parameters which are shown inFIG. 8 to FIG. 10.

$\begin{matrix}{\gamma = {{\arctan\left( \frac{Larm1\_ z}{Larm1\_ x} \right)} + {\arctan\left( \frac{Larm3\_ z2}{Larm3\_ x2} \right)} + {\arccos\left( \frac{{{Ltmp}\;}^{2} + {{Larm}\; 4^{2}} - {{Lbucket}\; 1^{2}}}{2 \star {{Ltmp}*{Larm}\; 4}} \right)} + {\arccos\left( \frac{{{Ltmp}\;}^{2} + {{Lbucket}\; 3^{2}} - {{Lbucket}\; 2^{2}}}{2 \star {{Ltmp}*{Lbucket}\; 3}} \right)} + {\arctan\left( \frac{Lbucket4\_ x}{Lbucket4\_ z} \right)} + \frac{\pi}{2} - \pi}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

As shown in FIG. 8, Larm3_z2 is a distance between the first link pin 47a and the bucket pin 15 in the zarm2 axial direction. Larm3_x2 is adistance between the first link pin 47 a and the bucket pin 15 in thexarm2 axial direction. As shown in FIG. 9, Ltmp is a distance betweenthe bucket cylinder top pin 12 b and the bucket pin 15. Larm4 is adistance between the first link pin 47 a and the bucket pin 15. Lbucket1is a distance between the bucket cylinder top pin 12 b and the firstlink pin 47 a. Lbucket3 is a distance between the bucket pin 15 and thesecond link pin 48 a. Lbucket2 is a distance between the bucket cylindertop pin 12 b and the second link pin 48 a. As shown in FIG. 10,Lbucket4_x is a distance between the bucket pin 15 and the second linkpin 48 a in an xbucket axial direction. Lbucket4_z is a distance betweenthe bucket pin 15 and the second link pin 48 a in a zbucket axialdirection. Here, a direction which links the bucket pin 15 and thecutting edge P of the bucket 8 as seen from the side is set as anxbucket axis and a direction that is perpendicular to the xbucket axisis set as a zbucket axis. The swing angle γ of the bucket 8 is an anglewhich is formed by the xbucket axis and the xarm1 axis. Ltmp describedabove is expressed by equation 6 below.

$\begin{matrix}{{{Ltmp} = \sqrt{{{Larm}\; 4^{2}} + {{Lbucket}\; 1^{2}} - {2{Larm}\; 4*{Lbucket}\; 1*\cos\;\phi}}}{\phi = {\pi + \sqrt{\frac{Larm3\_ z2}{Larm3\_ x2}} - \sqrt{\frac{{Larm3\_ z1} - {Larm3\_ z2}}{{Larm3\_ x1} - {Larm3\_ x2}}} - {\arccos\left\{ \frac{{{Lbucket}\; 1^{2}} + {{Larm}\; 3^{2}} - {bucket\_ cyl}^{2}}{2*{Lbucket}\; 1*{Larm}\; 3} \right\}}}}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

Here, as shown in FIG. 8, Larm3 is a distance between the bucketcylinder foot pin 12 a and the first link pin 47 a. Larm3_x1 is adistance between the bucket cylinder foot pin 12 a and the bucket pin 15in the xarm2 axial direction. Larm3_z1 is a distance between the bucketcylinder foot pin 12 a and the bucket pin 15 in the zarm2 axialdirection.

In addition, boom_cyl described above is a value obtained by adding aboom cylinder offset boft to a stroke length bss of the boom cylinder 10which is detected by the first angle detection unit 16 as shown in FIG.11. In the same manner, arm_cyl is a value obtained by adding an armcylinder offset aoft to a stroke length as of the arm cylinder 11 whichis detected by the second angle detection unit 17. In the same manner,bucket_cyl is a value obtained by adding a bucket cylinder offset bkoftwhich includes the minimum distance of the bucket cylinder 12 to astroke length bkss of the bucket cylinder 12 which is detected by thethird angle detection unit 18.

3. Calibration Device 60

The calibration device 60 is a device in the hydraulic shovel 100 forcalibrating the parameters which are necessary for computing the swingangles α, β, and γ described above and computing the position of thecutting edge of the bucket 8. The calibration device 60 is configured bya calibration system for calibrating the parameters described abovealong with the hydraulic shovel 100 and an external measurement device62. The external measurement device 62 is a device which measures theposition of the cutting edge of the bucket 8, and for example, is atotal station. The calibration device 60 can perform wired or wirelessdata communication with the external measurement device 62. In addition,the calibration device 60 can perform wired or wireless datacommunication with the display controller 39. The calibration device 60performs calibration of the parameters shown in FIGS. 6A and 6B based oninformation that is measured using the external measurement device 62.The calibration of the parameters is executed, for example, in aninitial setting at the time of shipping of the hydraulic shovel 100 orafter maintenance.

FIG. 12 is a flow chart illustrating a work sequence which is performedby an operator during calibration. First, in step S1, the operatorinstalls the external measurement device 62. At this time, the operatorinstalls the external measurement device 62 with a spacing of a certaindistance directly beside the boom pin 13 as shown in FIG. 13. Inaddition, in step S2, the operator measures the center position in theside surface of the boom pin 13 using the external measurement device62.

In step S3, the operator measures the position of the cutting edge atfive postures of the work implement 2 using the external measurementdevice 62. Here, the operator moves the position of the cutting edge ofthe bucket 8 to five positions from a first position P1 to a fifthposition P5 shown in FIG. 14 by operating the work implement operationmember 31. At this time, the pivoting body 3 is continuously fixedwithout rotation with respect to the travel unit 5. Then, the operatormeasures the coordinates of the cutting edge at each of the positions ofthe first position P1 to the fifth position P5 using the externalmeasurement device 62. The first position P1 and the second position P2are positions on the ground surface which are different in the front andback direction of the vehicle body. The third position P3 and the fourthposition P4 are positions in midair which are different in the front andback direction of the vehicle body. The third position P3 and the fourthposition P4 are positions which are different with regard to the firstposition P1 and the second position P2 in the upward and downwarddirection. The fifth position P5 is a position among the first positionP1, the second position P2, the third position P3, and the fourthposition P4. FIG. 15 lists the stroke lengths of each of the cylinders10 to 12 at each of the positions of the first position P1 to the fifthposition P5 with 100% as the maximum and 0% as the minimum. In the firstposition P1, the stroke length of the arm cylinder 11 is the minimum.That is, the first position P1 is a position of the cutting edge at aposture of the work implement 2 where the swing angle of the arm 7 isthe minimum. In the second position P2, the stroke length of the armcylinder 11 is the maximum. That is, the second position P2 is aposition of the cutting edge at a posture of the work implement 2 wherethe swing angle of the arm 7 is the maximum. In the third position P3,the stroke length of the arm cylinder 11 is the minimum and the strokelength of the bucket cylinder 12 is the maximum. That is, the thirdposition P3 is a position of the cutting edge at a posture of the workimplement 2 where the swing angle of the arm 7 is the minimum and theswing angle of the bucket 8 is the maximum. In the fourth position P4,the stroke length of the boom cylinder 10 is the maximum. That is, thefourth position P4 is a position of the cutting edge at a posture of thework implement 2 where the swing angle of the boom 6 is the maximum. Inthe fifth position P5, the stroke lengths of all of the arm cylinder 11,the boom cylinder 10, or the bucket cylinder 12 are intermediate valueswhich are not the minimum or the maximum. That is, at the fifth positionP5, all out of the swing angle of the arm 7, the swing angle of the boom6, and the swing angle of the bucket 8 are intermediate values which arenot the maximum or the minimum.

In step S4, the operator inputs the first working point positioninformation into an input unit 63 of the calibration device 60. Thefirst working point position information indicates the coordinates ofthe cutting edge of the bucket 8 at the first position P1 to the fifthposition P5 which are measured using the external measurement device 62.Accordingly, in step S4, the operator inputs, into the input unit 63 ofthe calibration 60, the coordinates of the cutting edge of the bucket 8at the first position P1 to the fifth position P5 which are measuredusing the external measurement device 62.

In step S5, the operator measures the positions of the antennas 21 and22 using the external measurement device 62. Here, as shown in FIG. 16,the operator measures positions of a first measurement point P11 and asecond measurement point P12 on the reference antenna 21 using theexternal measurement device 62. The first measurement point P11 and thesecond measurement point P12 are arranged to be symmetrical with respectto the center of the upper surface of the reference antenna 21. As shownin FIG. 16, the first measurement point P11 and the second measurementpoint P12 are two points on a diagonal on the upper surface of thereference antenna 21 if the shape of the upper surface of the referenceantenna 21 is a rectangle or a square. In addition, as shown in FIG. 17,the operator measures positions of a third measurement point P13 and afourth measurement point P14 on the direction antenna 22 using theexternal measurement device 62. The third measurement point P13 and thefourth measurement point P14 are arranged to be symmetrical with respectto the center of the upper surface of the direction antenna 22. Thethird measurement point P13 and the fourth measurement point P14 are twopoints on a diagonal on the upper surface of the direction antenna 22 inthe same manner as the first measurement point P11 and the secondmeasurement point P12. Here, it is preferable for marks to be added inthe first measurement point P11 to the fourth measurement point P14 inorder to facilitate the measurement. For example, bolts or the likeincluded as parts in the antennas 21 and 22 may be used as the marks.

In step S6, the operator inputs antenna position information into theinput unit 63 of the calibration unit 60. The antenna positioninformation includes coordinates which indicate the positions of thefirst measurement point P11 to the fourth measurement point P14 whichthe operator measures using the external measurement device 62 in stepS5.

In step S7, the operator measures three positions of the cutting edgewhere the rotation angle is different. Here, as shown in FIG. 18, theoperator carries out rotation of the pivoting body 3 by operating therotation operation member 51. At this time, the posture of the workimplement 2 is continuously fixed. Then, the operator measures the threepositions of the cutting edge where the rotation angle is different(referred to below as a “first rotation position P21”, a “secondrotation position P22”, and a “third rotation position P23”) using theexternal measurement device 62.

In step S8, the operator inputs the second working position informationto the input unit 63 of the calibration unit 60. The second workingposition information includes coordinates indicating the first rotationposition P21, the second rotation position P22, and the third rotationposition P23 which the operator measures using the external measurementdevice 62 in step S7.

In step S9, the operator inputs bucket information to the input unit 63of the calibration unit 60. The bucket information is information whichrelates to the dimensions of the bucket 8. The bucket informationincludes the distance (Lbucket4_x) between the bucket pin 15 and thesecond link pin 48 a in the xbucket axial direction and the distance(Lbucket4_z) between the bucket pin 15 and the second link pin 48 a inthe zbucket axial direction which are described above. The operatorinputs, as the bucket information, design values or values that aremeasured using a measurement means such as a measuring tape.

In step S10, the operator instructs the calibration device 60 to executethe calibration.

Next, a process executed by the calibration device 60 will be described.As shown in FIG. 3, the calibration device 60 has the input unit 63, adisplay unit 64, and a computation unit 65. The input unit 63 is a unitto which the first working point position information, the secondworking point position information, the antenna position information,and the bucket information described above are input. The input unit 63comprises a configuration for the operator to manually input theinformation described above, and for example, has a plurality of keys.The input unit 63 may be a touch panel as long as it is possible toinput numerical values. The display unit 64 is, for example, an LCD andis a unit that displays an operation screen for performing calibration.FIG. 19 illustrates an example of an operation screen of the calibrationdevice 60. An input column 66 for inputting the information describedabove is displayed in the operation screen. The operator inputs theinformation described above into the input column 66 of the operationscreen by operating the input unit 63.

The computation unit 65 executes the process of calibrating theparameters based on the information input via the input unit 63. FIG. 20is a functional block diagram illustrating a processing function relatedto calibration by the computation unit 65. The computation unit 65 haseach of the functions of a vehicle body coordinate system computationunit 65 a, a coordinate conversion unit 65 b, a first calibrationcomputation unit 65 c, and a second calibration computation unit 65 d.

The vehicle body coordinate system computation unit 65 a computes thecoordinate conversion information based on the first working pointposition information and the second working point position informationwhich are input using the input unit 63. The coordinate conversioninformation is information for converting the coordinate system withrespect to the external measurement device 62 to the vehicle bodycoordinate system. The first working point position information and theantenna position information described above are expressed using acoordinate system (xp, yp, zp) with respect to the external measurementdevice 62 because the first working point position information and theantenna position information are measured using the external measurementdevice 62. The coordinate conversion information is information forconverting the first working point position information and the antennaposition information in the coordinates with respect to the externalmeasurement device 62 to those in the vehicle body coordinate system (x,y, z). Below, the method for computing the coordinate conversioninformation will be described.

First, as shown in FIG. 21, the vehicle body coordinate systemcomputation unit 65 a computes a first unit normal vector AHperpendicular to an action plane A of the work implement 2 based on thefirst working point position information. The vehicle body coordinatesystem computation unit 65 a computes the action plane of the workimplement 2 using a least square method from the five positions includedin the first working point position information and then computes thefirst unit normal vector AH. Here, the first unit normal vector AH maybe computed based on two vectors a1 and a2 which are obtained using thecoordinates of three positions that are not as distant as the other twopositions out of the five positions included in the first working pointposition information.

Next, the vehicle body coordinate system computation unit 65 a computesa second unit normal vector perpendicular to a rotation plane B of thepivoting body 3 based on the second working point position information.Specifically, the vehicle body coordinate system computation unit 65 acomputes a second unit normal vector BH′ perpendicular to a rotationplane B′ based on two vectors b1 and b2 which are obtained using thecoordinates of the first rotation position P21, the second rotationposition P22, and the third rotation position P23 included in the secondworking point position information. Next, as shown in FIG. 22, thevehicle body coordinate system computation unit 65 a computes anintersection vector DAB of the rotation plane B′ and the action plane Aof the work implement 2 described above. The vehicle body coordinatesystem computation unit 65 a computes a unit normal vector of the planeB, which passes through the intersection vector DAB and is perpendicularto the action plane A of the work implement 2, as the second unit normalvector BH which is corrected. Then, the vehicle body coordinate systemcomputation unit 65 a computes a third unit normal vector CH which isperpendicular to both the first unit normal vector AH and the secondunit normal vector BH which is corrected.

The coordinate conversion unit 65 b converts, using the coordinateconversion information, the first working point position information andthe antenna position information, which are measured using the externalmeasurement device 62, in the coordinate system (xp, yp, zp) in theexternal measurement device 62 to those in the vehicle body coordinatesystem (x, y, z) in the hydraulic shovel 100. The coordinate conversioninformation includes the first unit normal vector AH, the second unitnormal vector BH which is corrected, and the third unit normal vector CHwhich are described above. Specifically, coordinates in the vehicle bodycoordinate system are computed using the inner product of vector p whosecoordinates are in the coordinate system of the external measurementdevice 62 and each of the normal vectors AH, BH, and CH in thecoordinate conversion information as shown in equation 7 below.x={right arrow over (p)}·{right arrow over (CH)}y={right arrow over (p)}·{right arrow over (AH)}z={right arrow over (p)}·{right arrow over (BH)}  Equation 7

The first calibration computation unit 65 c computes the calibrationvalues of the parameters by using numerical analysis based on the firstworking point position information that is converted into the vehiclebody coordinate system. Specifically, the calibration values of theparameters are computed using a least squares method as shown inequation 8 below.

                                      Equation  8$J = {{\frac{1}{2}{\sum\limits_{k = 1}^{n}\left\{ {{L\; 1\;{\sin\left( {\alpha\; k} \right)}} + {L\; 2\;{\sin\left( {{\alpha\; k} + {\beta\; k}} \right)}} + {L\; 3\;{\sin\left( {{\alpha\; k} + {\beta\; k} + {\gamma\; k}} \right)}} - {xk}} \right\}^{2}}} + {\frac{1}{2}{\sum\limits_{k = 1}^{n}\left\{ {{L\; 1\;{\cos\left( {\alpha\; k} \right)}} + {L\; 2\;{\cos\left( {{\alpha\; k} + {\beta\; k}} \right)}} + {L\; 3\;{\cos\left( {{\alpha\; k} + {\beta\; k} + {\gamma\; k}} \right)}} - {zk}} \right\}^{2}}}}$

The value of k, which is described above, represents the first positionP1 to the fifth position P5 in the first working point positioninformation. Accordingly, n=5. (x1, z1) are coordinates of the firstposition P1 in the vehicle body coordinate system. (x2, z2) arecoordinates of the second position P2 in the vehicle body coordinatesystem. (x3, z3) are coordinates of the third position P3 in the vehiclebody coordinate system. (x4, z4) are coordinates of the fourth positionP4 in the vehicle body coordinate system. (x5, z5) are coordinates ofthe fifth position P5 in the vehicle body coordinate system. Thecalibration values of the work implement parameters are computed bysearching for points where function J in equation 8 is minimized.Specifically, the calibration values of No. 1 to 29 of the workimplement parameters are computed using the lists in FIGS. 6A and 6B.Here, out of the work implement parameters included in the lists inFIGS. 6A and 6B, the distance Lbucket4_x between the bucket pin 15 andthe second link pin 48 a in the xbucket axial direction and the distanceLbucket4_z between the bucket pin 15 and the second link pin 48 a in thezbucket axial direction are set to values that are input as the bucketinformation for computation.

The second calibration computation unit 65 d calibrates the antennaparameters based on the antenna position information which is input intothe input unit 63. Specifically, the second calibration computation unit65 d computes the coordinates of the midpoint of the first measurementpoint P11 and the second measurement point P12 as the coordinates of theposition of the reference antenna 21. Specifically, the coordinates ofthe position of the reference antenna 21 are expressed using thedistance Lbbx between the boom pin 13 and the reference antenna 21 inthe x axial direction of the vehicle body coordinate system, thedistance Lbby between the boom pin 13 and the reference antenna 21 inthe y axial direction of the vehicle body coordinate system, and thedistance Lbbz between the boom pin 13 and the reference antenna 21 inthe z axial direction of the vehicle body coordinate system which aredescribed above. In addition, the second calibration computation unit 65d computes the coordinates of the midpoint of the third measurementpoint P13 and the fourth measurement point P14 as the coordinates of theposition of the direction antenna 22. Specifically, the coordinates ofthe position of the direction antenna 22 are expressed using thedistance Lbdx between the boom pin 13 and the direction antenna 22 inthe x axial direction of the vehicle body coordinate system, thedistance Lbdy between the boom pin 13 and the direction antenna 22 inthe y axial direction of the vehicle body coordinate system, and thedistance Lbdz between the boom pin 13 and the direction antenna 22 inthe z axial direction of the vehicle body coordinate system. Then, thesecond calibration computation unit 65 d outputs the coordinates of thepositions of the antennas 21 and 22 as the calibration values of theantenna parameters Lbbx, Lbby, Lbbz, Lbdx, Lbdy, and Lbdz.

The work implement parameters which are computed using the firstcalibration computation unit 65 c, the antenna parameters which arecomputed using the second calibration computation unit 65 d, and thebucket information are stored in the storage unit 43 of the displaycontroller 39 and are used in the computation of the position of thecutting edge described above.

4. Characteristics

The calibration system according to the embodiment has the followingcharacteristics.

The coordinates of the cutting edge of the bucket 8 at a plurality ofpositions, which are measured by the external measurement device 62, areconverted to the vehicle body coordinate system. Then, the calibrationvalues of the parameters are automatically computed by numericalanalysis based on the converted coordinates of the cutting edge of thebucket 8 at a plurality of positions in the vehicle body coordinatesystem. As a result, it is possible to reduce the number of parametersfor which actual measurement is necessary. In addition, it is notnecessary to perform rearrangement of the values of the parameters untilthe actual value and the computed value of the position coordinates ofthe cutting edge of the bucket 8 match during calibration. Hereby, inthe calibration system of the hydraulic shovel 100 according to theembodiment, it is possible to improve the accuracy of position detectionof the cutting edge and to shorten the calibration work time as well.

As shown in FIG. 21, the unit normal vector BH′ perpendicular to therotation plane B′ specified from the second working point positioninformation is not used as the second unit normal vector. At first, theintersection vector DAB of the action plane A of the work implement 2and the rotation plane B′ of the pivoting body 3 as shown FIG. 22 iscomputed. Then, the unit normal vector BH of the plane B, which passesthrough the intersection vector DAB and is perpendicular of the actionplane A of the work implement 2, is computed as the second unit normalvector. As a result, it is possible to accurately compute the vehiclebody coordinate system even in a case where the action plane A of thework implement 2 and the rotation plane B′ of the pivoting body 3 arenot strictly perpendicular. Hereby, it is possible to further improvethe accuracy of position detection of the cutting edge of the bucket 8.

The first working point position information includes coordinates of thefirst position P1 to the fifth position P5 which are different positionsin the upward and downward direction of the work implement 2 and/orwhich are different positions in the front and back direction of thevehicle body. It is possible to accurately compute the coordinateconversion information since the coordinates of various positions areused in this manner.

5. Other Embodiments

Above, an embodiment of the present invention has been described, butthe present invention is not limited to the embodiment described aboveand various modifications are possible as below within the scope whichdoes not depart from the gist of the invention.

In the embodiment described above, the bucket 8 is given as an exampleof the work tool, but work tools other than the bucket 8 may be used. Inaddition, the cutting edge of the bucket 8 is given as an example of theworking point, but in a case where a work tool other than the bucket 8is used, the working point may be a portion which comes into contactwith a work target object such as a point which is positioned at the tipend of the work tool.

In the embodiment described above, the swing angles α, β, and γ of theboom 6, the arm 7, and the bucket 8 respectively are computed from thestroke lengths of the cylinders but may be directly detected using anangle sensor.

The first working point position information is not limited to thecoordinates at the five positions of the cutting edge of the bucket 8described above. For example, the first working point positioninformation may include at least three positions of the working pointwhere the posture of the work implement 2 is different. In this case, itis sufficient if the three positions of the working point are not linedup on a single straight line and the position of one of the workingpoints is separated in the upward and downward direction or the frontand back direction of the vehicle body with regard to a straight linethat links the other two working points. In addition, in relation to thecomputation of the coordinate conversion information, the first workingpoint position information may include at least two positions of theworking point where the posture of the work implement 2 is different anda position of a predetermined reference point on the action plane of thework implement 2 (for example, a midpoint of the boom pin 13 in thevehicle widthwise direction).

In the embodiment described above, the first working point positioninformation, the second working point position information, and theantenna position information are input into the input unit 63 of thecalibration device 60 due to manual input by the operator, but may beinput into the input unit 63 of the calibration device 60 from theexternal measurement device 62 using a wired or wireless communicationmeans.

The external measurement device 62 is not limited to a total station andmay be another device which measures the position of the working point.

In the embodiment described above, the unit normal vector BH, where theunit normal vector BH′ that is perpendicular to the rotation plane B′specified from the second working point position information iscorrected, is used as the coordinate conversion information, but theunit normal vector BH′ may be used as the coordinate conversioninformation.

According to the illustrated embodiments, it is possible to provide acalibration system and a calibration method for a hydraulic shovel thatcan improve the accuracy of position detection of a working point andshorten calibration work time.

The invention claimed is:
 1. A hydraulic shovel calibration devicecomprising: a hydraulic shovel including a travel unit, a pivoting bodyrotatably attached to the travel unit, a work implement including a boomswingably attached to the pivoting body, an arm swingably attached tothe boom, and a work tool swingably attached to the arm, an angledetection unit configured to detect a swing angle of the boom withrespect to the pivoting body, a swing angle of the arm with respect tothe boom, and a swing angle of the work tool with respect to the arm,and a current position computation unit configured to compute a currentposition of a working point included in the work tool based on aplurality of parameters that indicate the swing angles and dimensions ofthe boom, the arm, and the work tool; a calibration device configuredand arranged to calibrate the parameters; and an external measurementdevice configured and arranged to measure a position of the workingpoint, wherein the calibration device includes an input unit configuredand arranged to input first working point position information andsecond working point position information, wherein the first workingpoint position information includes either at least two positions of theworking point where a posture of the work implement is different and aposition of a predetermined reference point on an action plane of thework implement, the at least two positions and the position of thepredetermined reference point being measured by the external measurementdevice, or at least three positions of the working point where theposture of the work implement is different, the at least three positionsbeing measured by the external measurement device, and the secondworking point position information includes at least three positions ofthe working point where a rotation angle of the pivoting body withrespect to the travel unit is different, a vehicle body coordinatesystem computation unit configured to compute a first unit normal vectorperpendicular to the action plane of the work implement based on thefirst working point position information, a second unit normal vectorperpendicular to a rotation plane of the pivoting body based on thesecond working point position information, and a third unit normalvector perpendicular to the first unit normal vector and the second unitnormal vector, a coordinate conversion unit configured to convertcoordinates at a plurality of positions of the working point measured bythe external measurement device in a coordinate system of the externalmeasurement device to those in a vehicle body coordinate system of thehydraulic shovel using the first unit normal vector, the second unitnormal vector, and the third unit normal vector, and a calibrationcomputation unit configured to compute calibration values of theparameters based on the coordinates converted by the coordinateconversion unit at the plurality of positions of the working point inthe vehicle body coordinate system.
 2. The hydraulic shovel calibrationsystem according to claim 1, wherein the vehicle body coordinate systemcomputation unit is configured to compute an intersection vector of theaction plane of the work implement and a rotation plane of the pivotingbody and to compute, as the second unit normal vector, a unit normalvector of a plane which passes through the intersection vector of theaction plane of the work implement and the rotation plane and which isperpendicular to the action plane of the work implement.
 3. Thehydraulic shovel calibration system according to claim 1, wherein thefirst working point position information includes coordinates of aplurality of positions which are different positions in an upward anddownward direction of the work implement and/or which are differentpositions in a front and back direction of the vehicle body.
 4. Thehydraulic shovel calibration system according to claim 1, wherein theparameters include a first distance between a swing pivot of the boomwith respect to the pivoting body and a swing pivot of the arm withrespect to the boom, a second distance between the swing pivot of thearm with respect to the boom and a swing pivot of the work tool withrespect to the arm, and a third distance between the swing pivot of thework tool with respect to the arm and the working point, the currentposition computation unit is configured to compute the current positionof the working point in the vehicle body coordinate system based on thefirst distance, the second distance, the third distance, and the swingangles, and the calibration computation unit is configured to computethe calibration values of the first distance, the second distance, andthe third distance based on coordinates at a plurality of positions ofthe working point which are measured by the external measurement deviceand converted into the vehicle body coordinate system.
 5. The hydraulicshovel calibration system according to claim 1, wherein the externalmeasurement device is a total station.
 6. A hydraulic shovel calibrationmethod for calibrating parameters in a hydraulic shovel, the hydraulicshovel including a travel unit, a pivoting body rotatably attached tothe travel unit, a work implement including a boom swingably attached tothe pivoting body, an arm swingably attached to the boom, and a worktool swingably attached to the arm, an angle detection unit configuredto detect a swing angle of the boom with respect to the pivoting body, aswing angle of the arm with respect to the boom, and a swing angle ofthe work tool with respect to the arm, and a current positioncomputation unit configured to compute a current position of a workingpoint included in the work tool based on a plurality of parameters thatindicate the dimensions and the swing angles of the boom, the arm, andthe work tool; the hydraulic shovel calibration method comprising:measuring a position of the working point using an external measurementdevice; inputting first working point position information and secondworking point position information into a calibration device forcalibrating the parameters, wherein the first working point positioninformation includes either at least two positions of the working pointwhere a posture of the work implement is different and a position of apredetermined reference point on an action plane of the work implement,the at least two positions and the position of the predeterminedreference point being measured by the external measurement device or atleast three positions of the working point where the posture of the workimplement is different, the at least three positions being measured bythe external measurement device, and the second working point positioninformation includes at least three positions of the working point wherea rotation angle of the pivoting body with respect to the travel unit isdifferent; computing a first unit normal vector perpendicular to theaction plane of the work implement based on the first working pointposition information, a second unit normal vector perpendicular to arotation plane of the pivoting body based on the second working pointposition information, and a third unit normal vector perpendicular tothe first unit normal vector and the second unit normal vector, usingthe calibration device; converting coordinates at a plurality ofpositions of the working point measured by the external measurementdevice in a coordinate system of the external measurement device tothose in a vehicle body coordinate system of the hydraulic shovel usingthe first unit normal vector, the second unit normal vector, and thethird unit normal vector, using the calibration device; and computingcalibration values of the parameters based on the converted coordinatesat the plurality of positions of the working point in the vehicle bodycoordinate system, using the calibration device.